Dig under the couch cushions and check your old pants pockets, because for $55 million, the Colorado Department of Transportation could make permanent highway improvements to reduce congestion on Interstate 70 in and around the Twin Tunnels near Idaho Springs.

It’s a relatively modest sum, considering the state’s general fund is $7 billion, but CDOT doesn’t have an extra $55 million stashed anywhere.

Still, we think CDOT should make this portion of I-70 — a long-studied but never-acted-upon corridor — a priority for funding, and should explore all funding options to make this improvement a reality.

A team of outside construction experts met in Colorado last week to brainstorm possible solutions to the congestion that bogs down traffic at the tunnels. They came up with several ideas, but settled on a preferred option that calls for widening the eastbound bore of the Twin Tunnels to three lanes and adding a third lane to eastbound I-70 between the east end of Idaho Springs and the base of Floyd Hill.

The option also includes flattening out the 45 mph curve in the eastbound lanes of I-70 just west of the Hidden Valley exit to allow for 55 mph traffic, according to a Denver Post story by Jeffrey Leib.

The Twin Tunnels are considered a choke point on I-70, snarling eastbound traffic especially as skiers head home in the winter and outdoor enthusiasts head down the hill in summer months. The congestion is not only aggravating for motorists, it also can be costly for business if goods can’t be shipped through the corridor in a timely manner.

It would be a shame to let this plan sit on a shelf, buried under dust and a pile of good intentions.

The Colorado legislature recently hiked vehicle registration fees to help fix some 125 deficient bridges in the state, but the FASTER fees, as they’re known, also created a pool of money that can be tapped for this type of project.

Also, we’ve always been intrigued by the concept of tolling on that portion of I-70 — if it can be done without the tollbooths that would slow traffic. (On E-470 and the Northwest Parkway, motorists are simply billed after a camera snaps a shot of their license plate.)

CDOT earlier explored the idea of creating “zipper lanes” on winter Sundays to ease congestion. It involved converting a lane of westbound I-70 on both sides of the Twin Tunnels to a reversible eastbound lane using moveable barriers.

It would have cut travel times between Georgetown and Evergreen in half on the limited number of winter Sundays but would double the travel time for westbound motorists.

And it was expensive.

“Why spend $25 million to $40 million [on zipper lanes] for 17 days a year when I’m giving you three lanes, 365 days a year for $55 million?” asked Peter Kozinski, an engineer on CDOT’s I-70 mountain corridor team.

Why, indeed.

CDOT should scrap any notion of zipper lanes and make paying for this project a priority.